1. Field of the Invention
This invention relates to an image forming device such as reproduction apparatus, and so forth.
2. Description of the Prior Art
There has so far been known a reproduction apparatus of a type, in which the process sequence control is carried out by a computer program. In this type of reproduction apparatus, however, as the apparatus becomes sophisticated in mechanism so that it may have versatile functions of high speed copying operation, of making reproduction copies on various sizes of paper, of automatic feeding of image originals, and so on, there inevitably occurs increase in the amount of information inputs for the reproduction, operating loads for simultaneous actuations of various components in the apparatus, and number of indicators and displays, whereby giving and receiving of signals within the reproduction apparatus becomes very frequent. On account of this, there would arise various inconveniences with the computer program which can primarily process those input data with a time sequence such that entry timing and entry pattern of the input informations relative to the copying operation are very limited, and an indicator for the copy number cannot be operated with the same time interval during execution of the sequence to thereby cause flickering.
In the conventional original automatic feeders (hereinafter abbreviated as "ADF"), there are such types that (1) feeding and discharging of the image originals are carried out in association with driving force of the reproduction apparatus without a driving source and a control section for its own being provided; and (2) feeding and discharging of the image originals are carried out by receipt of control signals from the reproduction apparatus with the driving soul for ADF's own being provided. However, it is extremely difficult and complicated in such subordinate relationship between ADF and the reproduction apparatus as mentioned above to positively discriminate the operating conditions for the ADF and to control the operational timing and prohibition of the operations. Also, when errors in input and output of the reproduction and detection informations increase, the key entry for the copying operations becomes impossible at all.
In the reproduction apparatus which continuously make copies depending on a preset number of copy sheets, an apparatus having such functions of interrupting its continuous copying operation, replacing an original image for copying, and, thereafter, executing copying of the remaining number of sheet for the continuous copying, i.e., interrupting function, has become common. In this type of reproduction apparatus, however, when the conditions for the interruption copying such as set number of sheet for interruption etc. are uniformly instructed to each of the process modes during execution of the copy cycle, or during interval between previous and subsequent copy cycles, or during stoppage prior to commencement or after termination of the copying operations, there arises such apprehension that the number of copy sheets, etc. before the interruption becomes difficult to be distinguished.
In the reproduction apparatus having the ADF, the feeding and discharging of the image originals are controlled in accordance with the reproduction operations, on account of which much time is required for setting the image original when the reproduction operation is stopped due to shortage in the reproduction paper, jamming of the reproduction paper, and others, after which such interrupted operation is released to resume the reproduction operation. In this consequence, there has been such inconveniences that resumption of the reproduction operation is delayed, and the reproduction speed is slowed down accordingly.
The reproduction apparatus in general has a function of detecting paper jammed in the reproduction apparatus and discontinuing the reproduction operations so as to prevent any trouble in the reproduction operations. This function is performed by a sensor provided in the paper feeding path, depending on whether it detects the paper at a predetermined timing, or not. However, in case the paper jamming takes place frequently to repeat interruption of the reproduction, such frequent disorder is due to the mechanical and electric component parts in the reproduction apparatus being out of order or operating erroneously. Also, when the sensor for detecting the paper jamming is out of order, it occurs sometimes that the reproduction operation is repeatedly interrupt in spite of the paper being regularly conveyed. Moreover, when the paper jamming takes place within the innermost part of the paper feeding path, it is difficult to locate the place where the paper jamming has taken place, and to remove the paper which is jammed, whereby re-starting of the reproduction operation becomes apprehensively impossible.
With the recent tendency to high performance and high speed operation in the reproduction apparatus, the electrical control section of the apparatus becomes highly sophisticated with the consequence that a very slight trouble in the electrical driving system in the machine develops into a serious disorder in the reproduction apparatus as a whole, hence its detection in operations. Even if the trouble is not so serious, considerable time and labor should be expended for repair and mending of the disordered machine.
The exposure surface of the image original mounting table in the reproduction apparatus (hereinafter simply called "platen") is subjected from time to time to breakage due to temperature increase through high temperature light irradiation or prolonged light irradiation. In order to prevent such temperature rise in the platen, there is sometimes provided a heat expelling blower to cool the surface of this platen or the neighborhood area of the exposure lamp. Even with provision of such heat expelling blower, the platen is exposed to a danger of high temperature due to continued reproduction operations over a long period of time, or reduction in operating function of this blower, or unusually continued lighting of the exposure lamp.
When two loads, which should not be driven simultaneously, such as the forwarding and returning clutches for reciprocating a scanning means in a conventional scanning type reproduction apparatus, happen to be operated simultaneously due to a disorder in the control means, it is not possible to foresee what kind of unexpected mechanical trouble would arise. Also, when very large operating loads of high electric consumption, which are not usually driven simultaneously, are driven at the same time, there would be high posibility of excessive electric current flowing through the circuit to bring about the short-circuit, and other dangerous situations.
Further, in some reproduction apparatuses, there is provided means for detecting oblique forwarding of the reproduction paper. In the apparatus of a system, wherein the oblique forwarding is detected with one pattern irrespective of whether the reproduction paper is large or small in size, even when the detected result reveals the regular forwarding with the small sized paper, jamming would sometimes take place with a large-sized paper.
In the reproduction apparatus of a type, wherein the jamming of the reproduction paper is detected and the machine is locked to be inoperative, if the release of the machine locking is done by a switch installed in the machine disregards the location of the jamming, the paper removing operation becomes extremely troublesome, in case the jammed paper can be taken out very easily.
In other type of the reproduction apparatus, there is such one that the number of the reproduction paper wasted by jamming is subtracted from the total number to be reproduce and the remaining number of the copy sheet is indicated on an indicator. It is, however, very difficult to determine the number of paper to be wasted by such jamming, when a plurality of sheets of paper exist in a long paper feeding path of the reproduction apparatus. In addition, removal of such plurality of sheets requires much labor, and takes long time until its re-starting.
In the conventional image-transfer type reproduction apparatus, the feeding of the image transfer paper has been controlled by detecting a particular reciprocating point of the exposure scanning system so as to carry out transfer of the toner image on the photosensitive body onto the image transfer paper in exact registration therebetween. However in case the paper feeding path for the image transfer paper is long, or the image transfer paper is continuously fed in the number of rollers for the paper feeding increases, or rotation of the rollers increases, with the consequence that there takes place slipping of the image transfer paper depending on its quality to make it difficult to perform accurate paper feeding, or to cause displacement in the image transfer position, or to cause paper jamming.
Weight of the reciprocating members such as optical system, image original mounting table, and so forth are rather heavy, hence the returning speed of these members is made higher than that at the time of the exposure so as to shorten the time for returning them to their original position after completion of the exposure. Accordingly, it occurs that the image original mounting table collides with the terminal end of the reciprocating motion at the end of the movement. With such collision of the reciprocating member, shock is imparted to the optical system and other components parts of the reproduction apparatus to disorder its optical axis, or shorten the life of the exposure lamp, or cause displacement in the transferred image.
In order to rectify a slant movement of the image transfer paper, the register roller to forward the paper to the image transfer section forms a slackened portion or loop in the image transfer paper, after which it sends the image transfer paper to the image transfer position by its rotation at a predetermined timing which coincides with the tip end of the formed image at the image transfer position. However, in case the quantity of the slackened portion is not accurately controlled, the image transfer operation is done without the slant movement being sufficiently rectified, or, to the worst of the case, jamming of the paper is resulted.